An Integrated Multidisciplinary Approach by Assessing Treatment Approaches and Tracking Clinical Progress

Abstract

Chest wall deformities represent a diverse spectrum of conditions encountered frequently in pediatrics’ medical practice. They manifest with various phenotypic expressions and, although typically benign, can lead to significant physiological and psychological impacts, some of which pose life-threatening risks. To facilitate systematic understanding, these deformities can be categorized into distinct groups, including: (1) pectus excavatum, (2) pectus carinatum, (3) Poland syndrome, (4) sternal defects, and (5) pectus arcuatum. This chapter aims to comprehensively elucidate these deformities, providing insights into their non-surgical and surgical management, including the latest diagnostic and treatment modalities. Additionally, it delves into the psychological and physiological ramifications experienced by young patients and their families, thereby offering a holistic understanding of the impact of these conditions on their lives.

1. Introduction

Chest wall deformities are commonly observed and vary widely in appearance. Although generally benign, they can lead to significant physiological complications. These are categorized into: (1) pectus excavatum, (2) pectus carinatum, (3) Poland syndrome, (4) sternal defects, and (5) pectus arcuatum.

2. Pectus excavatum

Pectus excavatum (PE), also known as “funnel chest,” represents the predominant congenital malformation of the anterior chest wall, accounting for 90% of all anterior chest wall deformities. The prevalence of this condition ranges among 1 in every 400 to 1000 live births, and it is three to five times more common in males than in females. While often occurring isolated, pectus excavatum can also be associated with connective tissue disorders, neuromuscular diseases, and genetic syndromes [1, 2].

PE usually becomes noticeable shortly after birth, marked by a posterior indentation of the lower sternum and a curvilinear deformation of the nearby costal cartilages. The deformity primarily affects the lower three to four ribs at their connection to the sternum, while the upper chest including the manubrium, the upper sternum, and the first three ribs remains typically unaffected. Pectus excavatum may also appear asymmetrically, often with the right side more concave, and can include a rotational deviation of the sternum toward the more depressed side.

2.1 Etiology

Although the exact etiology of pectus excavatum remains undetermined, several theories have been proposed. These hypotheses include an imbalance in the growth rates of the ribs compared to the thoracic organs; disproportionate muscular forces exerting unusual stress and strain on the sternum and costal cartilages; anomalies in cartilage structure and growth; irregular rib development; or a combination of these [3].

A significant proportion of pectus excavatum (85–90%) emerge as isolated defect, shortly after birth. Nevertheless, this condition frequently co-occurs with connective tissue disorders, with Marfan syndrome being prevalent. It is also linked to other connective tissue disorders such as Ehlers-Danlos syndrome and osteogenesis imperfecta [4, 5].

In addition to these, there is a substantial link with neuromuscular diseases, for example, spinal muscular atrophy.

Other genetic conditions observed in association with pectus excavatum are Noonan syndrome, Turner syndrome, neurofibromatosis type 1, and multiple endocrine neoplasia type 2b [6].

The higher incidence of pectus excavatum in individuals with connective tissue disorders points to a potential underlying cause rooted in atypical cartilage development like an imbalance in the genetic regulation of cartilage, between genes that promote growth and those that inhibit it [1].

Despite these hypotheses, specific genetic triggers have yet to be identified. Furthermore, histological examinations of cartilage samples from individuals with PE have consistently shown normal tissue structures [7].

The link between congenital diaphragmatic anomalies (diaphragmatic hernia and agenesis) and pectus excavatum is clear because both conditions are often associated [8, 9].

Additionally, there is a significant association between pectus excavatum and scoliosis [10].

There is a pattern of familial aggregation, with approximately one-third of patients reporting at least one family member who has a similar chest wall deformity [11].

2.2 Clinical presentation

2.2.1 Physical findings

On physical examination, is evident the typical depression in the anterior chest wall, primarily affecting the lower half of the sternum and adjacent ribs, and possibly extending laterally up to the mid-clavicular line. The lower costal margins often exhibit an outward flare. Asymmetry, when present, generally shows a deeper indentation on the right side, accompanied by a rotational shift of the sternum from left to right (Figures 1 and 2).

Figure 1.

Frontal view pectus excavatum.

Figure 2.

Lateral view pectus excavatum.

Lung sounds are usually normal, but a systolic murmur may be detected, which in some cases is only audible when the patient is in a sitting or standing position.

2.2.2 Symptoms

Symptoms can typically be categorized into three main areas: pain, difficulty with exercise, or concerns regarding physical appearance.

In a comprehensive evaluation of patients with severe pectus excavatum, the reported symptoms included [12]:

• Exercise intolerance in 82% of cases,

• Chest pain in 68%,

• Reduced endurance in 67%, and

• Shortness of breath in 42% of the individuals assessed.

The pain is often sharp and brief, localized to the area of the sternal indentation, and can happen sporadically or be triggered by physical activity. Exercise intolerance tends to be of moderate severity. Interestingly, even highly active individuals might find their athletic performance slightly lagging behind their peers.

Concerns about appearance become particularly significant during adolescence, a period often marked by self-consciousness and the desire to fit in. Being perceived as “different” can attract unwanted attention, making the physical manifestations of this condition a source of distress for many young people.

Among patients, females have shown a higher tendency to raise concerns about their physical appearance compared to males (68 vs. 40%). Yet, the level of concern about appearance does not consistently align with the severity of pectus excavatum, indicating a varied perception of the condition’s impact among individuals [13].

2.3 Evaluation

Patients with pectus excavatum require an assessment to determine the deformity’s severity and identify any coexisting conditions. Those with moderate-to-severe PE, or those exhibiting symptoms indicative of cardiorespiratory compromise, should undergo CT scan.

However, a retrospective study has shown a weak correlation between the physical symptoms and the deformity’s severity as seen on chest CT scans [14].

Nevertheless, patients presenting with respiratory symptoms, or those being considered for surgery, should have a pulmonary function test to check for any restrictive respiratory conditions. Exercise tests may be conducted on select patients to assess cardiopulmonary limitations. In cases of significant heart displacement or cardiopulmonary constraints, assessments should include echocardiography and electrocardiography.

For patients not initially recommended for surgery, regular monitoring with focused physical exams is advised, especially during adolescence. This allows for prompt identification and management of any worsening in the deformity or related symptoms, and consideration of non-surgical treatment options.

2.3.1 Physical examination

Thoracic abnormalities—Beyond the hallmark indentation of the sternum, patients with pectus excavatum frequently exhibit a reduced chest wall diameter from front to back and possess a chest that appears wide and flat, and commonly exhibits a kyphotic curve. A significant proportion of those with pectus excavatum (10 to 39%) also experience varying degrees of scoliosis. The emergence of scoliosis can occur at any point during the evolution of pectus excavatum, and the impact of corrective pectus surgeries on the evolution of scoliosis remains uncertain [15].

Respiratory symptoms—Up to 98% of patients with pectus excavatum experience resting tachypnoea, which becomes more pronounced during adolescence. Those with more advanced stages of PE often exhibit a diminished aerobic capacity. It is rare to observe significant upper or lower respiratory tract anomalies during physical assessments. Approximately 42% of affected individuals report experiencing shortness of breath [12].

Cardiac assessment—In cases of isolated pectus excavatum, cardiac irregularities are uncommon. However, individuals with PE who also have associated syndromic conditions are more susceptible to cardiovascular issues.

Severe PE may lead to tachycardia, attributed to diminished stroke volume, which in turn is related to the heart’s distortion and displacement. A small subset of patients may exhibit functional systolic murmurs, potentially linked to the compression of the left ventricular outflow tract. Additionally, mitral valve prolapse has been observed in a minority of those with PE.

2.3.2 Imaging and index score

Chest X-ray—Standard chest X-rays, including anteroposterior and lateral views, offer limited insight of the deformity but are valuable in identifying accompanying conditions such as kyphoscoliosis or pulmonary disorders.

In certain healthcare settings, conventional radiographs are employed to calculate the Pectus Severity Index (PSI), also known as the Haller Index. However, this method is not as uniformly standardized as CT imaging and may yield less accurate results, particularly for chests with asymmetrical deformities [16].

The PE deformity may present characteristic features on the frontal X-ray, such as opacification in the region of the right middle lobe. This shadowing is often confused with right middle lobe pneumonia or atelectasis but is the result of compression by the anterior chest wall’s soft tissues [17].

More than half of the individuals with PE may show a shift of the heart’s outline to the left on frontal images [18].

Lateral views show the sternum’s posterior displacement, as an opacity that fills the space behind the sternum, with the ribs extending in front of it [17].

Computed tomography scan—CT scans are indicated for patients presenting with moderate to severe pectus excavatum or those experiencing cardiorespiratory difficulties. CT scans are the gold standard to assess the extent of the pectus deformity, including the level of cardiac and pulmonary compression, the displacement of the heart, lung atelectasis, chest wall asymmetry, rotation of the sternum, and the potential development of a compensatory barrel chest.

Magnetic resonance imaging—MRI has also proven effective for these evaluations, offering a significant benefit by avoiding radiation exposure [19].

The Pectus Severity Index—PSI, also known as the Haller Index, provides a precise measure of sternal depression severity. It quantifies the depth of the pectus deformity by calculating the ratio of the chest’s transverse diameter to its anteroposterior diameter. This measurement is taken from the sternum’s posterior surface to the vertebral body’s anterior surface at the deepest point of the deformity [20].

A PSI value of ≤2.5 is considered within the normal range, and typically, patients with a PSI of <3.25 are not considered for surgical intervention [21].

These figures, especially when integrated with additional assessments like pulmonary function tests and cardiovascular evaluations, help in identifying candidates for whom surgical intervention is advisable (Figure 3) [22, 23].

Figure 3.

Haller index on CT scan.

The Pectus Correction Index (PCI)—has been developed as an alternative to the Haller Index, which might not always capture the true severity of pectus excavatum in cases of atypical chest wall shapes.

The PCI quantifies the proportion of chest depth affected by the pectus deformity.

To calculate the PCI, first imagine the sternum corrected to its ideal position and draw a hypothetical horizontal line across the back at this level. The PCI is calculated by taking the distance from this hypothetical line to the front of the vertebra and subtracting the distance from the deepest point of the sternum’s depression to the vertebra. The difference is then divided by the distance from the hypothetical line to the vertebra, and the result is multiplied by 100 to convert it into a percentage.

The PCI is particularly valuable for assessing the severity of pectus deformities in individuals with unusual chest shapes, such as exceptionally wide or narrow chests. A PCI value of 28 per cent or higher, corresponding to a Pectus Severity Index (PSI) of at least 3.25, typically indicates a significant deformity that may warrant surgical intervention [24].

3D body scan—Both the Haller Index (HI) and the Pectus Correction Index (PCI) were initially designed for evaluation through computed tomography. However, the risk associated with ionizing radiation, especially for pediatric patients, raises a significant concern.

As a result, there is a growing interest in, radiation-free, three-dimensional (3D) optical surface imaging as an alternative diagnostic tool.

Given that three-dimensional images concern the external surface, the conventional Haller index, and correction index are not applicable as these are based on internal diameters.

Therefore, external equivalents have been introduced for three-dimensional images. However, cut-off values to help determine surgical candidacy using external indices are not standardized.

A recent paper applied 3D surface imaging to establish the external Haller Index, introducing the external Correction Index.

The authors established cut-off values for 3D imaging-derived indices, aligning them with established criteria for surgery: a conventional Haller Index of ≥3.25 and a CT-derived Correction Index of ≥28.0%.

This analysis identified optimal thresholds for surgical consideration: an external Haller Index of ≥1.83 and an external Correction Index of ≥15.2% [25].

In another study, researchers compared the accuracy of optical body surface scanning to conventional CT scans, using a 3D sensor, concluding that this can be effectively used for treatment monitoring [26].

2.3.3 Pulmonary function studies

Pulmonary function testing is recommended for individuals with moderate-to-severe pectus excavatum or those presenting respiratory symptoms. Despite the prevalence of respiratory complaints among PE patients, less than a third exhibit pulmonary function abnormalities, with a weak correlation between subjective symptoms and objective findings [27].

However, normal pulmonary function tests do not rule out the potential cardiopulmonary limitations during physical activity.

Research by Kelly et al. in a cohort of patients seeking surgical correction for PE revealed significant reductions in Forced Vital Capacity (FVC), Forced Expiratory Volume in 1 second (FEV1) and Forced Expiratory Flow at 25–75% (FEF25-75%). These metrics were approximately 10% to 15% lower than the expected averages for the general population [28].

Another study examining lung function before and after the Nuss procedure indicated significant improvements in lung function tests post-surgery, with more pronounced improvements in older patients, showing a trend toward normalization [29].

However, these improvements, while statistically significant, are modest and unlikely to fully account for reported increases in stamina and exercise capacity [30].

2.3.4 Exercise testing

The interest in this topic began with observations by Dr. Sauerbruch, a prominent German thoracic surgeon. He described a case of a 19-year-old, the son of a Swiss watchmaker, who could not sustain a full day’s work due to his condition. After surgery to correct his PE, the young man experienced a notable improvement in endurance, able to work longer hours without fatigue. This case inspired numerous studies to objectively evaluate if PE truly affects heart and lung function and to what extent surgical interventions can improve these functions [31].

Exercise testing is advised for individuals with moderate-to-severe PE, or those who show significant respiratory symptoms. This test is more effective at identifying cardiopulmonary abnormalities compared to resting spirometry tests because it evaluates how the cardiac and pulmonary systems interact dynamically under stress.

Small-scale studies have documented diminished maximal exercise capabilities, including lower peak oxygen consumption (VO2max), attributed to decreased stroke volume, alongside a reduced VO2max and an earlier onset of lactate accumulation during physical exertion [21, 32].

Patients with PE may experience an increased metabolic cost of breathing, related to the mechanical inefficiencies of their respiratory system [33].

2.3.5 Cardiac function

Patients with significant displacement of the heart observed on imaging, or those experiencing cardiopulmonary limitations should undergo a cardiology evaluation, including echocardiography and electrocardiography.

Echocardiography might not always confirm cardiac compression; however, it screens potential cardiac manifestations of Marfan syndrome (Mitral valve prolapse and evaluation of the aortic root), and Turner or Noonan syndrome.

In a large series of female patients, 68% showed electrocardiographic evidence of right ventricular strain [7].

Echocardiography has revealed subtle right ventricular outflow obstruction and reduced right ventricular systolic function in severe pectus excavatum cases [34, 35], with improvements noted post-surgery [36, 37].

Studies using intraoperative transoesophageal echocardiography have demonstrated relief of right heart chamber compression and improved cardiac output immediately following surgical repair [38].

2.3.6 Psychological impact

In recent decades, the research literature on anterior congenital chest wall malformations has increasingly focused on the impact on quality of life and psychological well-being.

Pectus excavatum, in particular, exerts a substantial negative psychological impact on patients, leading to significant distress and persistent self-evaluation [39]. Patients often experience embarrassment about their physical appearance, avoiding situations that expose their chest, such as during sports activities or intimate encounters, and report instances of teasing (experienced by 22.8% of patients), primarily from peers [40]. The experience of being teased serves as a strong motivator for seeking help. Psychometric assessments like the Child Behavior Checklist for ages 4 to 18 years (CBCL/4-18) have highlighted psychopathological aspects related to the condition, including withdrawal, anxiety, depression, and social difficulties [41].

Adolescents between 12 and 16 years old with severe malformations appear to be at higher risk of experiencing psychosocial problems, often characterized by low self-esteem, feelings of inferiority, depression, shyness, and social anxiety, which can impact their developmental progress during puberty [42].

While less is known about the experiences of females with these conditions, it is widely acknowledged that they face physiological limitations and esthetic concerns. Female patients with funnel chest deformities often present with asymmetric and underdeveloped chests [43, 44]. Recent research [45] suggests that young female patients with pectus excavatum may have a more challenging experience compared to males, often reporting negative emotions, withdrawal, and poor self-perception. Surveys such as the Modified Pectus Excavatum Evaluation Questionnaire (PEEQ) [46] indicate that patients over 15 years old are significantly more concerned about their appearance, although positive expectations regarding corrective measures remain high in both genders (around 75%). Parents, however, often express uncertainty (67%) or weak support (76%) for surgery, with greater concern for their female children (38.9%). The psychosocial dimension of these conditions extends to the entire family and can influence their expectations regarding treatment options.

While surgery is not recommended for very young patients due to the risk of relapse [47] and potential scarring [48], non-invasive methods such as vacuum bell, bracing, and exercise offer effective alternatives [49].

Studies on the quality of life in patients with pectus excavatum consistently demonstrate improvements in psychological well-being following corrective procedures [50]. Despite increased physical activity post-surgery, adolescents’ perceptions of Health-Related Quality of Life (HRQL) are heavily influenced by body image considerations [51].

Comparatively less is known about body image disturbances in patients with pectus carinatum, which often present primarily esthetic concerns rather than cardiopulmonary symptoms. The Pectus Carinatum Body Image Quality of Life (PeCBI-QOL) questionnaire [52], developed to assess psychological repercussions, highlights the importance of treatment motivation and engagement from both patients’ and parents’ perspectives, with significant improvements observed across all areas following treatment. Non-surgical correction using braces has also shown statistically significant improvements in children’s body self-image [53]. Patient compliance is essential for successful non-surgical treatment [54, 55].

2.3.7 Non-surgical approach

Non-surgical options, such as Vacuum bell, are significantly underutilized despite strong evidence supporting their effectiveness, which is comparable to surgery in the majority of cases and do not prevent patients from opting for surgical correction in the future if desired [56].

Treatment decisions should be well-informed and individualized. Considering the results, it is essential to recognize that no patient should be selected for surgery without first attempting a non-operative approach.

The vacuum bell—The most well-known non-surgical treatment for pectus excavatum is the vacuum bell. This device, inspired by suction cup dent pullers used in automobile repairs, was first utilized for treating pectus excavatum in Germany in 1910 [57].

The vacuum bell consists of a silicone ring and a transparent polycarbonate window, creating a vacuum at the chest wall using a hand pump operated by the patient. This vacuum can reach up to 15% below atmospheric pressure. Various sizes of the vacuum bell are available, allowing for selection based on the patient’s age and the shape of their chest.

The vacuum bell can significantly lift the ribs and sternum, leading to a permanent correction (Figure 4).

Figure 4.

Vacuum bell.

Indications—Almost all patients with pectus excavatum are potential candidates for vacuum bell therapy. The best results are typically seen in patients who begin therapy between the ages of 10–12, have a moderate pectus depth (≤ 1.8–1.5 cm), possess sufficient chest wall flexibility, and commit to at least 12 months of treatment [58].

Chest wall flexibility can be assessed by observing sternal elevation when applying the vacuum bell or using the Nuss maneuver:

• Having the patient lie supine with an exposed chest.

• Applying upward pressure on the sternum using a hand or a pectus lifter device, mimicking the surgical bar’s effect.

• Visually or instrumentally measuring the sternum’s elevation.

Older patients, those with more severe deformities, and those with asymmetric pectus excavatum can also benefit from vacuum bell therapy, though they may experience partial correction or require a longer treatment duration. Patients experiencing symptoms like exercise intolerance or chest pain can find relief with vacuum bell therapy.

Contraindications—Cardiac anomalies, skeletal disorders (such as osteogenesis imperfecta and Glisson’s disease), vasculopathies (including Marfan syndrome and aortic aneurysms), and coagulopathies are all contraindications for vacuum bell therapy.

Comprehensive history and physical examination should include a detailed family history and an echocardiogram to check for any valvular or aortic diseases. A chest CT may be necessary to calculate the Haller index. Depending on individual circumstances, additional tests such as pulmonary function tests, genetic testing, and photographic documentation of the pectus excavatum may also be required (Figures 5 and 6).

Figure 5.

PE pre-treatment.

Figure 6.

PE post-treatment with vacuum bell.

Daily use and treatment length—There is no standardized protocol for the frequency and duration of vacuum bell therapy, as these factors depend on the patient’s individual decision and motivation. The initial use of the vacuum bell takes place during an outpatient clinic visit under the supervision of the physician. The correct size and model are chosen based on the patient’s age, the shape of the chest wall, and their perception of the deformity. The centre of the device should be aligned with the deepest part of the pectus excavatum.

The general recommendation is to begin using the device twice daily for 30 minutes each session. The ideal daily usage is 4 hours, divided into two sessions, in the morning and in the evening, after a gradual increase [59].

Research indicates that sustained use of the vacuum bell for at least 12–18 months leads to more significant and lasting corrections. Remarkable improvements can be achieved even with shorter daily usage [60, 61, 62, 63].

Consistency and adherence over the entire duration of treatment are paramount for achieving optimal results.

The appropriate pressure varies greatly among patients. Patients are encouraged to apply enough pressure to feel their chest rise without causing pain, and they should expect their tolerance to increase as they become more used to the device. It is important for patients to understand that higher pressures do not necessarily correlate with better outcomes.

Outcomes—The vacuum bell has shown to be a highly effective treatment option for certain patients with pectus excavatum. Studies have indicated nearly 100% patient satisfaction, with most patients avoiding surgery. Approximately 20% of patients achieve complete correction, while around 37–80% experience partial correction [59].

The impact of vacuum bell therapy on cardiopulmonary function continues to be debated. The severity of pectus excavatum does not consistently predict symptoms, and clinical improvements following treatment appear to be influenced by multiple factors.

Complications—Generally, patients tolerate the vacuum bell well. Reported complications are mild, including chest wall pain, skin irritation, hematoma, and paraesthesia in the upper extremities. These issues typically resolve on their own once the treatment is discontinued.

Vacuum bell as an adjunct to surgery—Several experts and medical centres are exploring the use of the vacuum bell as a complement to traditional surgical treatments for pectus excavatum. A sterilized vacuum bell can be utilized to elevate the sternum without necessitating additional incisions during the Nuss procedure. It has also been considered for children potentially facing surgery, serving two primary purposes: 1) potentially eliminating the need for surgical intervention and 2) enhancing chest wall flexibility, which could lead to improved surgical outcomes and reduced post-operative discomfort.

Autologous fat grafting—The psychosocial impact of pectus excavatum can be significant, often justifying corrective measures. While even minimally invasive surgical repairs can leave scars, which might cause psychological distress in children, autologous fat grafts offer a less invasive alternative. Suitable for patients with sufficient fat reserves, this method can be used on its own or as a supplement to surgical approaches to enhance cosmetic outcomes.

Hyaluronic acid injections—Hyaluronic acid, widely used in esthetic treatments, presents a non-surgical option for enhancing the appearance of pectus excavatum. Applied as a filler, it aims to improve the visual aspect of the deformity without altering the sternal position. Its effectiveness remains a subject of debate.

2.3.8 Surgical repair

Surgical correction of pectus excavatum often enhances physical appearance and can improve cardiorespiratory function for some patients.

For patients with moderate-to-severe pectus excavatum, a CT scan is recommended to calculate the Pectus Severity Index (PSI).

Surgical intervention is typically considered for patients meeting two or more of the following criteria:

• A PSI greater than 3.25, as measured by CT scan.

• Evidence of cardiac compression, displacement, mitral valve prolapses, murmurs, or conduction abnormalities.

• Pulmonary function tests indicating restrictive respiratory disease.

• History of unsuccessful previous pectus excavatum repair

• Progression of the deformity, with either worsening physiological symptoms or significant patient concern regarding appearance.

There is evidence suggesting that children who undergo early surgical interventions may face a higher risk of recurrence during their adolescent years. Additionally, extensive resection of costal cartilage in young children has sometimes been found to inhibit chest wall growth [60, 62].

The ideal time for corrective surgery for a pectus defect is no earlier than 8 years of age, extending up to the end of adolescence. Children within this age range typically have sufficiently flexible costal cartilage for effective remodeling, while also being old enough to minimize the risk of recurrence during the puberty.

Nuss procedure—This minimally invasive approach developed in the 1990s by Nuss and his team involves correcting the chest deformity without removing any cartilage [61, 63].

The technique uses a custom-shaped metal bar, known as the Nuss bar, which is inserted into the pleural space, positioned behind the sternum at its most inward point, then rotated 180 degrees and secured to the ribs’ outer sides.

Modifications to the original Nuss procedure include making small cuts in the cartilage to relieve sternal pressure and better secure the bar, using lateral stabilizers, and employing multiple bars for more complex or extensive deformities.

The bar is typically removed after 2 to 3 years.

Postoperative pain—Patients who undergo the Nuss procedure often experience more postoperative pain compared to those who undergo Ravitch procedure. However, studies involving large patient groups have demonstrated that perioperative pain management is effectively maintained with both procedures, with postoperative pain typically resolving within 1 month.

A significant advancement in managing this postoperative pain is the use of cryoablation of the intercostal nerves in the area of repair. This method temporarily halts the nerves’ ability to transmit pain signals without affecting overall nerve function, which allows for the eventual healing and restoration of normal sensation and movement. When combined with intercostal nerve blocks, cryoablation has been shown to significantly enhance pain control post-surgery, reducing or even eliminating the need for opioid pain relievers [64, 65].

Bar displacement—Bar displacement or migration is a serious complication. In some instances, the bar may rotate (90 or 180 degrees posteriorly) or shift laterally. Historically, this issue affected 10 to 20 per cent of patients. However, thanks to increased surgical expertise and technical enhancements in stabilizer designs, the incidence of bar displacement has significantly decreased. Current stabilizing techniques include the use of metal stabilizers, pericostal sutures or wire fixation, and employing two bars when necessary to enhance stability [66].

Cardiac complications—Cardiac perforation can rarely occur during the retrosternal dissection required for placing the Nuss bar in the retrosternal space [67, 68].

Elevating the sternum with an external device can improves visibility and access to the retrosternal area. Additionally, the use of transoesophageal echocardiography has been adopted to ensure safer retrosternal dissection and accurate placement of the Nuss bar.

Pleural effusion—Pleural effusions are a known complication following the Nuss procedure, affecting about 3 per cent of patients. These typically develop around 2 weeks post-operation [69].

Ravitch procedure—The Ravitch procedure, firstly performed in the 1940s [70], has undergone several modifications aimed at enhancing the stability of the sternum internally, optimizing the correction quality, and reducing complications.

Initially, the technique involved extensive resection of the costal cartilages’ deformity, removal of the perichondrium, separation of the xiphoid process from the sternum, and a transverse osteotomy of the sternum. The sternum was then positioned anteriorly in an overcorrected position, secured by Kirschner wires or durable silk sutures.

Subsequent revisions by Baronofsky [71] and Welch [72] highlighted the critical role of preserving the perichondrium and its sternal attachments, facilitating rib regeneration. A significant later enhancement involved the incorporation of a support strut, inserted either through or beneath the sternum, to maintain structural integrity while the ribs regenerated.

Typically, these support struts, initially metal, are removed 6- to 12-month post-operation. More recent innovations include the use of bioabsorbable materials or Marlex mesh, though no conclusive evidence favors these newer materials over traditional metal struts in terms of effectiveness.

A key complication of the modified Ravitch procedure is the risk of developing a constricted thorax or secondary thoracic dystrophy, often referred to as acquired Jeune syndrome. This issue can arise from removing too much of the costal cartilage, including the growth centres, or from excessive strain on the perichondrium and damage to the growth centres.

As a result, the chest wall may not grow normally, restricting the development of the lungs and leading to significantly reduced lung capacities.

Risk factors for this condition include surgery before the age of four, removing five or more rib cartilages, disrupting the growth area near the sternum, and improperly aligning the perichondral sheaths.

To lower the risk, it is advisable to delay chest surgery until the child is at least 8 years old and to limit the removal to four or fewer rib cartilages.

Outcomes—There is a lack of extensive prospective studies directly comparing the outcomes of the Nuss and Ravitch procedures.

Patients generally report improved self-esteem and physical appearance following both the modified Ravitch and Nuss procedures. Improvements in exercise tolerance and some cardiopulmonary function metrics have also been observed with both surgical methods.

The outcomes for pulmonary function following the Nuss procedure can vary. Typically, there is an initial dip in lung function after the insertion of the Nuss bar, which then either returns to baseline or improves after the bar’s removal.

Additionally, many patients note better exercise capacity post-surgery. For both the Nuss and modified Ravitch procedures, objective measures such as maximum oxygen uptake (VO2 max) tend to remain stable or show modest improvements post-operatively [29, 73].

3. Pectus carinatum

3.1 Evaluation

Pectus carinatum (PC) is the second most prevalent chest wall deformity in children, following pectus excavatum. The name is derived from the Latin term meaning “chest with a keel.” This chest wall deformity is also commonly referred to as chicken breast, pigeon chest, pyramidal chest, cuneiform thorax, or sternal kyphosis. It usually does not cause symptoms and is primarily treated for cosmetic reasons.

It affects approximately 1 in 1500 live births and is often found in conjunction with genetic conditions such as Marfan, Noonan, and Poland syndromes. This deformity is more common in males, with a prevalence four times higher than in females, and exhibits a strong genetic link, as up to 25% of patients have a family history of similar chest abnormalities (Figure 7) [11, 74, 75].

Figure 7.

Pectus carinatum.

There are two primary forms of this deformity:

Chondrogladiolar prominence—Commonly referred to as chicken breast or keel chest, this is the most prevalent form of pectus carinatum. It features a forward protrusion of the middle and lower sections of the sternum. The costal cartilages typically show a concave and symmetrically depressed appearance, which emphasizes the sternal prominence. However, the deformity presents asymmetrically in 30 to 50 per cent of cases. Occasionally, patients may exhibit a mixed condition with pectus carinatum on one side and pectus excavatum on the other.

Chondromanubrial prominence—Also known as pectus arcuatum, pouter pigeon breast, or Currarino-Silverman syndrome, this form is a more complex and rarer type of pectus carinatum. In this variation, the upper part of the sternum protrudes forward, while the central section is shorter and leans backward. This creates a distinct Z-shaped appearance of the sternum when viewed from the side. This subtype usually arises from early hardening or the lack of proper segmentation of the sternal joints, resulting in a sternum that is both short and sharply angled. It is often linked with other bone or heart anomalies or with Noonan syndrome. Bracing treatments, unlike with other forms, are generally ineffective for this condition [76].

For many patients evaluated for pectus carinatum, the primary concern is cosmetic, with few physiological complaints reported. However, some patients experience exertional dyspnoea, exercise limitations, frequent respiratory infections, or asthma prior to surgery; these symptoms generally resolve following surgical correction.

The evaluation for pectus carinatum includes a physical examination to assess the severity of the defect. Imaging is typically reserved for those who will undergo surgical treatment as part of their preoperative evaluation.

During the examination, clinicians should document the type of deformity (chondrogladiolar, chondromanubrial, or a mixed carinatum/excavatum), and the degree of asymmetry. It is also important to check if the defect can be manually corrected by applying pressure to the sternum. The presence of scoliosis or other associated abnormalities should be noted.

Photographs are a valuable tool for objective documentation and for comparing changes over time.

Typically, the evaluation includes chest radiographs to document the severity of the deformity and to detect and monitor any scoliosis. Computed tomography scans are used for preoperative planning but are not routinely recommended for patients who are not proceeding to surgery.

For measuring the severity of pectus carinatum, the Pectus Severity Index or Haller index is used. A normal value is 2.54; a lower PSI in patients with pectus carinatum indicates a more severe deformity, which contrasts with pectus excavatum where a higher PSI indicates greater severity.

3.2 Treatment

Pectus carinatum is primarily considered a cosmetic issue, and the decision to treat is based on the severity of the defect and the concerns of the patient and their family. Both bracing and surgery are safe and effective treatment options (Figures 8 and 9).

Figure 8.

Brace.

Figure 9.

Brace in place.

Bracing—This should be the first line of treatment for patients with mild-to-moderate pectus carinatum. It tends to be more successful in patients with flexible chest walls who are committed to following the bracing regimen. Recent advancements in bracing techniques, which use lower pressures, have improved patient compliance and achieved good outcomes.

Surgery—Surgery may be the preferred option for patients with severe pectus carinatum, those who are skeletally mature, or those suffering from severe pectus arcuatum, as bracing is often less effective in these cases. It is also an option for patients with less severe deformities who are unwilling or unable to comply with a bracing regimen, but only if they have begun their pubertal growth spurt. Surgery should be delayed until after the onset of puberty to minimize the small but significant risk of asphyxiating thoracic dystrophy, particularly following the modified Ravitch repair for pectus carinatum.

4. Poland syndrome

Alfred Poland, a medical student at Guy’s Hospital in London, described a patient with a missing anterior chest wall in 1841. This condition, later named “Poland syndrome” (PS) by Clarkson, another physician at the same hospital, involves the absence of chest wall structures on one side (usually the right) and often includes syndactyly of the hand on the same side. Poland syndrome is rare, with an estimated occurrence of 1 in 30,000. It typically presents with a range of abnormalities from underdeveloped chest muscles and ribs to complete absence of the breast and nipple.

While chest deformities are a significant concern, the associated limb abnormalities, such as underdeveloped and fused fingers, are often more disabling. Poland syndrome may also coexist with Mobius’ syndrome, characterized by facial and abducens nerve palsies [77, 78].

Hashim et al., in their recent translational analysis, provide a comprehensive overview of the current theories regarding the genesis, evolution, and management of this syndrome [79].

Multiple theories and etiological factors have been proposed to explain the origins of congenital disorders, which result from errors in morphogenesis leading to malformations, deformations, or disruptions. One prominent theory involves embryonic or foetal vascular disruption, which can cause a sequence of developmental disruptions.

The vascular disruption theory is widely accepted as a pathogenic mechanism. It suggests that PS may arise from a disruption in the development of the proximal subclavian artery and its branches that supply the pectoral muscles around the sixth week of gestation. This disruption leads to inadequate blood flow to the distal limb and pectoral region, resulting in tissue loss in these areas. Bavinck and Weaver introduced a pathogenic hypothesis known as the “subclavian artery supply disruption sequence” (SASDS) to describe this vascular disruption during embryonic development [80].

The predictable patterns of defects resulting from SASDS include:

• Absence of the pectoralis major and ipsilateral breast hypoplasia due to interruption of internal thoracic artery flow.

• Terminal transverse limb defects following a disruption of the subclavian artery distal to the origin of the internal thoracic artery.

• Poland syndrome resulting from a disruption of the subclavian artery distal to the origin of the vertebral artery but proximal to the origin of the internal thoracic artery.

Various factors, including mechanical, environmental, and embryologic events, can lead to interruption or reduction of blood flow to the subclavian artery and its branches. Intrinsic factors such as thrombi and emboli, as well as external mechanical influences like cervical ribs, aberrant muscles, and amniotic bands, can cause vascular disruption [81, 82, 83].

Other suggested hypotheses include maternal factors, such as smoking and cocaine abuse [84].

Genetic or external factors can disrupt the migration of the pectoralis major muscle and digital separation during the critical period between 6 and 8 weeks of gestation. While most PS cases are sporadic, familial instances have been documented, suggesting a possible autosomal dominant inheritance pattern with variable penetrance. These familial cases exhibit intra-familial variability [85, 86].

Moderate-to-severe PS is typically diagnosed at birth due to visible chest or limb defects. Antenatal diagnosis through foetal ultrasound can detect these abnormalities, and Doppler assessment of the ipsilateral subclavian artery flow is recommended when unilateral skeletal defects are identified. Three-dimensional US enhances the characterization of limb defects [87].

Clinical suspicion of PS arises upon detecting chest defects with or without ipsilateral limb anomalies in newborns or children. The age of diagnosis varies widely due to the spectrum of severity, with some cases presenting later in life for unrelated medical issues, particularly in individuals with milder forms of PS and normal hand development.

Imaging modalities are essential for diagnosing PS and determining the specific location and characteristics of chest wall deformities. Chest X-rays typically reveal hyperlucency in the affected lung field, resembling a “post-radical mastectomy picture.” Both CT and MRI are paramount for accurate diagnosis, assessing the extent of musculoskeletal involvement, and guiding surgical reconstruction decisions.

Generally, surgical intervention in Poland Syndrome (PS) may be required for the following indications:

1. Unilateral depression of the chest wall that may worsen with age.

2. Insufficient protection of the lung and heart.

3. Paradoxical movement of the chest wall.

4. Hypoplasia or aplasia of the breast in females.

5. Enhancement of the chest’s esthetic appearance in males due to the absence of the pectoralis major muscle and anterior axillary fold.

Surgical correction is tailored to the extent of chest involvement. For simple cases with only breast and muscle deficiencies, the treatment is cosmetic, using myo-cutaneous flaps, fat transfers, and prosthetics. More complex cases, involving missing ribs, require structural repairs. Generally, surgery is recommended after growth completion to ensure the best outcomes, except in urgent situations like lung herniation that causes breathing difficulties.

5. Conclusion

In conclusion, chest wall deformities in pediatric patients, while typically benign, can have profound physiological and psychological impacts. Emphasizing conservative management strategies is essential, as they are often sufficient in addressing mild-to-moderate cases and can significantly reduce the need for invasive surgical procedures. Early and accurate diagnosis, coupled with regular monitoring, is crucial to promptly address any potential complications and ensure optimal patient outcomes.

A multidisciplinary approach is key in the management of these conditions. Pediatricians, thoracic surgeons, physical therapists, and mental health professionals should work collaboratively to develop comprehensive and individualized care plans. This approach not only addresses the physical aspects of the deformities but also supports the psychological well-being of the young patients and their families.

Non-surgical interventions, such as physical therapy, bracing, and respiratory exercises, can be highly effective in managing symptoms and improving quality of life. When surgical intervention is necessary, it should be carefully considered and tailored to the specific needs of the patient, ensuring that the benefits outweigh the risks.

Ultimately, the goal is to provide holistic care that prioritizes the overall health and well-being of the patient. By focusing on conservative management and fostering a supportive care environment, healthcare providers can help young patients with chest wall deformities lead healthier, more fulfilling lives.